In general, adaptive control techniques using an adaptive digital filter have been widely used for the purpose of reducing vibration and noise, and many techniques including Filtered-X LMS (Least Mean Square) and the like have been proposed. For a structure of an adaptive filter, also, various structures including an FIR (Finite Impulse Response) filter and a SAN (Single-frequency Adaptive Notch) filter have been proposed.
Among them, for adaptive control targeting a periodic signal of engine vibration of an automobile, in terms of an improvement in a control operation amount and a filter convergence, a technique to configure the adaptive digital filter by using the SAN filter has been mainly popularly used.
Further, Patent Document 1 proposes an active vibration suppressing device which, by driving an electromagnetic actuator upon adaptive control aiming at a position where vibration is detected and having a maximum control deviation, suppresses vibration at the position. Further, various methods of the adaptive control have been proposed (for example, see Patent Document 2).